The present invention relates to an improved point for cutting tools, and more particularly to a drill bit with a unique point surface adapted for extended wear.
Most drill points are machine point ground and a variety of drill point styles are known and particularly adapted for specific drilling tasks. For example, the 118.degree. general purpose drill bit is the most commonly used drill point and gives satisfactory results in a wide variety of materials. The Racon is another known style point and forms a relatively large arc with its curved lips and has a rounded lip corner reducing corner wear and eliminating burrs at exit. Split point drill points are known in the art for being self-centering and requiring less torque and thrust in hand or machine drilling. The Double Angle point is used in drilling of abrasive materials. The double angle on this point acts as a chamber concentrating tool wear along the entire cutting lip and reducing corner wear. A helical drill point has a "S" shaped chisel making the point self-centering and requiring less torque and thrust. Insert drill bits are also known in the art wherein insert tips of varying sizes and profiles are interchangeable with the body of a drill bit.
Regardless of the shape of the chisel or lip curvature, the life of the drill point depends on how well the point dissipates heat. If the point does not adequately conduct heat away from its cutting edges, the temperature buildup will "burn" the point and diminish the life of the drill bit. The heat generated at the lip of the drill point is directly related to the load and stresses the lip is subjected to. The more efficiently load stresses are dissipated, the less heat is built up at the cutting edge of the drill point. The Racon point mentioned above attempts to minimize stress by curving the cutting lip. Although this point does offer an improvement, heat dissipation and wear are still critical concerns in the art.
Applicant's present invention offers a significant improvement in the art, providing a unique drill point having distinct wear advantages over conventional drill points.